A variety of microwave susceptor-containing packages have been previously proposed for absorbing microwave energy and transmitting it by conduction to crisp and brown the surface of the food product. Some prior susceptors were stiff, brittle, subject to breakage or otherwise unsuited for use in lightweight, disposable and low cost packaging. In other cases the susceptor, while interacting with the microwave energy present in an oven, does not adequately heat or crisp the food product. Other susceptors heat only one side of the food product. So, for example, if the food product is rectangular in shape, two or three sides remain pale and uncrispened. The susceptor itself shold be easy to insert into the package and, once inserted, should be retained securely in place.
U.S. Pat. Nos. 4,612,431 and 4,735,513 describe a susceptor formed from polyester film to which a thin, semicondcutive layer of metal is applied. Tests conducted in the development of the present invention show, however, that these laminates and the resulting packages are not effective in crisping, browning or toasting the surface of a food such as a french fried potato. After heating, the product still tends to be perceived as somewhat moist, limp and soggy. To overcome these problems, a package was developed which is much more effective in crisping the surface of stick-shaped food pieces. Different forms of this package are described in U.S. Pat. Nos. 4,943,439 and 5,034,234. These designs provide a microwave susceptor package that will crisp, toast or brown several surfaces of a stick-shaped food product such as french fried potatoes, fish sticks or the like so that the food is perceived to be crisp and appetizing to the consumer. They do, however, have certain shortcomings. The food is difficult to cool, i.e. hot moisture vapor tends to remain trapped inside, the food receiving tray is small, tends to tip over, has no room for condiments and is expensive to manufacture.
In view of these shortcomings of the prior art, it is a major objective of the invention to provide an improved microwave food heating package which includes a serving tray and in which much more efficient cooling of the package can be accomplished. A further objective is to provide a package of the type described having a serving tray of substantial width and length with a broad base and a wide mouth into which the hot food sticks can be easily poured from the inner portion of the carton. Another object is to provide an improved package of the type described having a wide serving tray with a low profile to provide room for other food ingredients such as condiments, salt and the like and which is less expensive to manufacture than the serving tray described in U.S. Pat. No. 5,034,234.